During surgery on the heart or lung it is sometimes necessary to provide a substitute means of oxygenation of returning venous blood. Excess carbon dioxide carried by the blood must be removed, and oxygen added in its place. One known and commonly used means of performing oxygenation is to inject oxygen into the blood in such a manner as to create a foam of blood bubbles and to rely on gas diffusion through the thin blood walls of each bubble to accomplish oxygenation. The difference in partial pressures of oxygen and carbon dioxide between the interiors of the bubbles and the blood walls causes the simultaneous inward diffusion of oxygen and outward diffusion of carbon dioxide through the blood walls. To stabilize the blood foam and make uniform the oxygenation rate, it is known to provide narrow gas exchange tubes and chambers narrow in one dimension in which the bubbles rise and diffusion occurs. To break up the blood bubbles after oxygenation, it is conventional to pass them through a defoamer which uses surfactant materials applied to a reticulated foam material. As with other extracorporeal blood treatment, it is desirable to warm or cool the blood before returning it to the patient. To accomplish this, temperature-controlled water is circulated past heat-conductive walls through which heat is transferred to or from the blood.
Travenol Laboratories, Inc., has on the market a heat exchanger for blood in which the heat exchange medium is a corrugated metal sheet. Blood in its ordinary liquid state is passed along one side of the sheet and a temperature-controlled liquid is passed along the other side.
Brumfield et al. U.S. Pat. No. 3,807,958 and Brumfield et al. U.S. Pat. No. 3,768,977, show blood oxygenators with vertical tubular gas exchange passages passing through a bath of heat exchange fluid.
Bowley U.S. Pat. No. 3,960,657 shows a bubble type blood oxygenator that uses a column of glass beads to define gas exchange passages.